1. Field of the Invention
The present invention relates to a ball grid array-type high frequency semiconductor device housing package for mounting and housing therein a high frequency semiconductor device for use in, for example, a microwave or millimeter wave region, and to a mounting structure for mounting the same. More particularly, the invention relates to a high frequency semiconductor device housing package that provides improved efficiency of high frequency signal transmission and also provides high mounting yields, and to a mounting structure for mounting the same.
2. Description of the Related Art
Conventionally, a high frequency semiconductor device housing package for use in a high-frequency range such as a microwave or millimeter wave region is constructed as follows. For example, on a base substrate made of metal is placed a metallic frame body and the like to constitute a wall portion. The metallic frame body constituting the wall portion has a notch formed in one part thereof. In this notch portion is provided an input/output terminal by fitting and bonding that has a line-conversion structure constituted by a combination of micro-strip line/strip line (triplate line)/micro strip line, which is obtained by stacking dielectric layers one on top of another. Then, after a semiconductor circuit device for use in a high-frequency range is mounted within the package, a lid body made of metal or a dielectric material is attached thereon by soldering, welding, or other techniques.
Moreover, in such a high frequency semiconductor device housing package, the input/output terminal, acting as an interface between the semiconductor circuit device housed therewithin and an external electric circuit is commonly shaped as a planar circuit, like a micro-strip line. Thus, for establishing connection with the external electric circuit, on a ground surface having a flat plane, like a bottom surface of a metal chassis, are arranged the circuit board of the external electric circuit and the input/output terminal which is designed to be possibly uniform in height with the circuit board, and their strip lines are connected to one another by a gold wire or the like. In a case where it is difficult to make the circuit board and the input/output terminal uniform in height, their strip lines are mutually connected by wire bonding with the difference in height left between the circuit board and the input/output terminal. Otherwise, if possible, wire bonding is carried out after the ground surface is suitably processed so that the input/output terminal is possibly uniform in surface height with the circuit board.
However, the above-described conventional high frequency semiconductor device housing package has the following disadvantage. In a high-frequency range, in particular a millimeter wave region, in order to suppress occurrence of unnecessary mode in signal transmission, the constituent components need to be made as small as possible in dimension. As a result, formation of a notch in the wall portion, fabrication of the input/output terminal, or assembling process for these components need to be performed with remarkably high accuracy. This makes difficult the manufacture of the high frequency semiconductor device housing package, and thus leads to an undesirable increase in the manufacturing cost.
There arises another problem involved in the connection with the external electric circuit. In a high-frequency band such as a millimeter wave region, if wire bonding is carried out with the difference in height left in the mounting surface, the transmission characteristics are deteriorated. Even in a case where the ground surface is suitably processed, the discontinuity of the height of the ground surface can lead to deterioration in the transmission characteristics. Still another problem is that, likewise to the above, the hollowing of the bottom surface of the chassis or other processing needs to be achieved with remarkably high accuracy.
Further, a problem is encountered also in the operation for mounting the high frequency semiconductor device housing package with respect to the circuit board. The input/output terminal and the external electric circuit need to be positioned relative to each other by butting with high accuracy, and this makes the mounting operation difficult.
As a consequence, there is an increasing demand for such a high frequency semiconductor device housing package that is manufacturable solely with a production process based on a thick film printing technique suitable for mass production and a technique for realizing a multilayer structure of dielectric layers such as ceramics, and that provides satisfactory high-frequency characteristics and has a mounting structure in which stable mounting accuracy can be obtained in a simple manner.
The invention has been devised to solve the above stated problems associated with the conventional art, and to satisfy the requirements on a high frequency semiconductor device housing package. Accordingly, an object of the invention is to provide a ball grid array-type high frequency semiconductor device housing package that is manufacturable by a thick film printing technique suitable for mass production and a multilayer technique for use with dielectric layers such as ceramics, and that provides satisfactory high-frequency characteristics and has a structure in which stable mounting accuracy can be obtained in a simple manner. Another object of the invention is to provide amounting structure for mounting the same.
The invention provides a high frequency semiconductor device housing package, comprising:
an insulating substrate having on its one surface a mounting and housing portion for mounting and housing therein a high frequency semiconductor device;
a plurality of wiring conductors that are electrically connected to an electrode of the high frequency semiconductor device, the wiring conductors being so arranged as to extend from the mounting and housing portion through another surface of the insulating substrate opposite to the one surface, the wiring conductors including a signal wiring conductor and a grounding wiring conductor;
a ball-shaped signal terminal that is arranged on the other surface of the insulating substrate, the ball-shaped signal terminal being electrically connected to the signal wiring conductor included in the wiring conductors; and
a plurality of ball-shaped grounding terminals that are arranged on the other surface of the insulating substrate and electrically connected to the grounding wiring conductor included in the wiring conductors, the ball-shaped grounding terminals being arranged substantially circularly so as to surround the centered ball-shaped signal terminal.
According to the invention, on an under surface, i.e. the other surface of the insulating substrate are arranged a plurality of ball-shaped signal terminals and a plurality of ball-shaped grounding terminals that are electrically connected to the wiring conductors. The ball-shaped grounding terminals are plurally arranged substantially circularly so as to surround the centered ball-shaped signal terminal. In this construction, the ball-shaped signal terminal can be defined as a signal conductor for a coaxial line, and the ball-shaped grounding terminal can be defined as a grounding conductor for the coaxial line. Accordingly, the high-frequency signal fed from the circuit board to the ball-shaped signal terminal can be transmitted efficiently.
In the invention, it is preferable that the ball-shaped grounding terminals are arranged substantially circularly at intervals equal to or less than one quarter of a signal wavelength of a high-frequency signal.
According to the invention, by arranging the ball-shaped grounding terminals substantially circularly at intervals equal to or less than one quarter of a signal wavelength of a high-frequency signal, in a space sandwiched between the under surface of the insulating substrate of the package and the top surface of the circuit board, a high-frequency signal can be successfully prevented from leaking from the ball-shaped signal terminal to the outside of the region surrounded by the ball-shaped grounding terminals. Accordingly, the high-frequency signal fed from the circuit board to the ball-shaped signal terminal can be transmitted more efficiently.
In the invention, it is preferable that the insulating substrate has on its other surface a grounding conductor layer with a circular opening centered about the ball-shaped signal terminal, and that on the grounding conductor layer around the opening are arranged the ball-shaped grounding terminals substantially circularly.
According to the invention, the insulating substrate has on its under surface, i.e. the other surface, a grounding conductor layer with a circular opening centered about the ball-shaped signal terminal. Moreover, on the grounding conductor layer around the opening are arranged the ball-shaped grounding terminals substantially circularly. In this construction, a high-frequency signal can be effectively prevented from entering the interior of the insulating substrate by the grounding conductor layer formed on the under surface of the insulating substrate of the package and the ball-shaped grounding terminal connected thereto. Consequently, the high-frequency signal fed from the circuit board to the ball-shaped signal terminal can be transmitted far more efficiently.
In the invention, it is preferable that the insulating substrate has on its other surface a line conductor which is connected to the ball-shaped signal terminal, and that the grounding conductor layer is provided with a grounding conductor layer non-exist portion extending from the opening through the line conductor.
According to the invention, the insulating substrate has on its under surface, i.e. the other surface, a line conductor which is connected to the ball-shaped signal terminal. Moreover, the grounding conductor layer is provided with a grounding conductor layer non-exist portion extending from the opening through the line conductor. In this construction, a high-frequency signal can be effectively prevented from entering the interior of the insulating substrate, and thus the high-frequency signal fed from the circuit board to the ball-shaped signal terminal can be transmitted efficiently. Besides, by providing the line conductor connected to the ball-shaped signal terminal, it is possible to enhance the wiring flexibility in the under surface of the insulating substrate. Moreover, the line conductor is surrounded by the grounding conductor layer via the grounding conductor layer non-exist portion and is thus realized as a coplanar line. Consequently, a high-frequency signal can be transmitted satisfactorily.
In the invention, it is preferable that the opening has a radius which is set to be 0.3 times or less longer than the signal wavelength of the high-frequency signal.
According to the invention, the radius of the opening is set to be 0.3 times or less longer than the signal wavelength of the high-frequency signal. This equates to setting a cut-off frequency of the TE-11 mode to be higher than the signal frequency of the high-frequency signal in a case where the opening of the grounding conductor layer is regarded as an opening of a circular waveguide filled with a dielectric material which is identical with the material used for the insulating substrate. Accordingly, at the signal frequency band, unnecessary mode conversion into a waveguide mode can be sufficiently suppressed in the ball-shaped signal terminal, and thus the high-frequency signal fed from the circuit board to the ball-shaped signal terminal can be transmitted efficiently.
The invention further provides a mounting structure for mounting a high frequency semiconductor device housing package, comprising:
a high frequency semiconductor device housing package including: an insulating substrate having on its one surface a mounting and housing portion for mounting and housing therein a high frequency semiconductor device; a plurality of wiring conductors that are electrically connected to an electrode of the high frequency semiconductor device, the wiring conductors being so arranged as to extend from the mounting and housing portion through another surface of the insulating substrate opposite to the one surface, the wiring conductors including a signal wiring conductor and a grounding wiring conductor; a ball-shaped signal terminal that is arranged on the other surface of the insulating substrate, the ball-shaped signal terminal being electrically connected to the signal wiring conductor included in the wiring conductors; and a plurality of ball-shaped grounding terminals that are arranged on the other surface of the insulating substrate and electrically connected to the grounding wiring conductors included in the wiring conductors, the ball-shaped grounding terminals being arranged substantially circularly so as to surround the centered ball-shaped signal terminal; and
a circuit board having on its one surface a signal terminal mounting pad corresponding to the ball-shaped signal terminal and a grounding conductor with a circular opening centered about the signal terminal mounting pad,
wherein the high frequency semiconductor device housing package is mounted on the circuit board in such a way that the ball-shaped signal terminal is electrically connected to the signal terminal mounting pad, and that the ball-shaped grounding terminal is electrically connected to the grounding conductor.
According to the invention, the high frequency semiconductor device housing package embodying the invention is mounted on the circuit board that has on its top surface, i.e. one surface, the signal terminal mounting pad corresponding to the ball-shaped signal terminal and the grounding conductor with a circular opening centered about the signal terminal mounting pad, in such a way that the ball-shaped signal terminal and the ball-shaped grounding terminal are electrically connected to the signal terminal mounting pad and the grounding conductor, respectively. In this construction, the ball-shaped signal terminal and the signal terminal mounting pad can be defined as signal conductors for a coaxial line, and the ball-shaped grounding terminal and the grounding conductor can be defined as grounding conductors for this coaxial line. Accordingly, in the mounting area, a high-frequency signal can be prevented from entering the interior of the circuit board, and further, by the junction in the form of the coaxial line, the high-frequency signal fed from the circuit board to the ball-shaped signal terminal can be transmitted efficiently.
In the invention, it is preferable that the grounding conductor has an opening whose radius is set to be 0.3 times or less longer than the signal wavelength of the high-frequency signal.
According to the invention, the radius of the opening provided in the grounding conductor of the circuit board is set to be 0.3 times or less longer than the signal wavelength of the high-frequency signal. This equates to setting a cut-off frequency of the TE-11 mode to be higher than the signal frequency of the high-frequency signal in a case where the opening of the grounding conductor is regarded as an opening of a circular waveguide filled with a dielectric material which is identical with the material used for the circuit board. Accordingly, at the signal frequency band, unnecessary mode conversion into a waveguide mode can be sufficiently suppressed in the signal terminal mounting pad, and thus the high-frequency signal fed from the signal terminal mounting pad of the circuit board to the ball-shaped signal terminal can be transmitted efficiently.
In any of those cases stated above, by exploiting a self alignment effect, which is conventionally well known in the field of the ball-shaped terminal mounting technology, high mounting accuracy can be ensured using a simple mounting method suitable for mounting work automation, such as the collective reflow mounting method, and variation in the high frequency transmission characteristics resulting from mounting variation can be suppressed. Consequently, it is possible to achieve mounting with high mounting yields.
According to the invention, there is provided a high frequency semiconductor device housing package that is manufacturable by a thick film printing technique suitable for mass production and a multilayer technique for use with dielectric layers such as ceramics, and that provides satisfactory high-frequency characteristics and has a structure in which stable mounting accuracy can be obtained in a simple manner, and as well a mounting structure for mounting the same is also provided.